Visualization of the dynamics of synaptic vesicle and plasma membrane proteins in living axons.
Newly synthesized membrane proteins are transported by fast axonal flow to their targets such as the plasma membrane and synaptic vesicles. However, their transporting vesicles have not yet been identified. We have successfully visualized the transporting vesicles of plasma membrane proteins, synaptic vesicle proteins, and the trans-Golgi network residual proteins in living axons at high resolution using laser scan microscopy of green fluorescent protein-tagged proteins after photobleaching. We found that all of these proteins are transported by tubulovesicular organelles of various sizes and shapes that circulate within axons from branch to branch and switch the direction of movement. These organelles are distinct from the endosomal compartments and constitute a new entity of membrane organelles that mediate the transport of newly synthesized proteins from the trans-Golgi network to the plasma membrane.
Nakata
T
T
Department of Cell Biology and Anatomy, Graduate School of Medicine, University of Tokyo, Hongo, Tokyo, Japan, 113.
Terada
S
S
Hirokawa
N
N
D000818:Animals; D001370:Axonal Transport; D001369:Axons / Q000378:metabolism* / Q000648:ultrastructure; D002478:Cells, Cultured; D011992:Endosomes / Q000378:metabolism / Q000648:ultrastructure; D019922:GAP-43 Protein / Q000378:metabolism; D005727:Ganglia, Spinal; D006056:Golgi Apparatus / Q000378:metabolism / Q000648:ultrastructure; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018613:Microscopy, Confocal; D016253:Microscopy, Immunoelectron; D009419:Nerve Tissue Proteins / Q000378:metabolism; D015388:Organelles / Q000378:metabolism* / Q000648:ultrastructure; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism; D020917:Receptor, trkA; D017475:Receptors, Nerve Growth Factor / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013572:Synaptic Vesicles / Q000378:metabolism* / Q000648:ultrastructure; D016708:Synaptophysin / Q000378:metabolism*; D050825:Synaptosomal-Associated Protein 25
D019922:GAP-43 Protein; D008164:Luminescent Proteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D011518:Proto-Oncogene Proteins; D017475:Receptors, Nerve Growth Factor; D011993:Recombinant Fusion Proteins; C494209:Snap25 protein, mouse; D016708:Synaptophysin; D050825:Synaptosomal-Associated Protein 25; D049452:Green Fluorescent Proteins; D020794:Receptor Protein-Tyrosine Kinases; D020917:Receptor, trkA